Facilitating exercise using externally applied, transcutaneous stimulation, including by sending electrical pulses to contract or otherwise activate the targeted or involved muscles, is known in the art. Typically, the electrical pulses applied are generated by an external stimulator, and travel through associated wires to one or more electrode pairs placed on the skin adjacent the muscle(s) to be contracted. The electricity passing through the skin causes the targeted muscle fibers to activate or contract, even without voluntary control by the subject. Accordingly, such stimulation is frequently used in situations where the subject is incapacitated or otherwise unable to control function of the muscles, such as in the event of an injury to the brain or associated portion of the nervous system.
Despite the widespread past use of electrical stimulation for exercising muscles, certain limitations in the application of this technology and the results produced remain. Specifically, the application of the stimulation is often based on “ramp and hold” type patterns that are externally applied based on timing. The application of such a pre-determined level of stimulation at a fixed interval is usually divorced from any volitional movement of the subject, and instead is applied by the clinician in an attempted synchronization with the exercise movement. Aside from being extremely unnatural, the benefit afforded by such an approach is not maximized in terms of encouraging the subject to make volitional contributions to the exercise.
Accordingly, a need is identified for a manner in which to apply an electrical stimulation to a subject based on a volitional exercise motion by that subject. Further, a need is identified for a manner in which to combine the benefits achieved through such a coordinated electrical stimulation based on volitional movement in a stepping exercise.